Idle mode is a working mode of mobile station (MS) in a mobile broadband wireless access system defined in IEEE 802.16e. In the idle mode, an MS moves in a very large area, and receives downlink broadcast service messages in a certain period interval. The MS is informed by the broadcast messages whether there is a downlink service to be sent. When roaming in the area, the MS does not need to register with a base station (BS) of the cell which it is roaming in. Meanwhile, when the MS roams to different cells, it is unnecessary to perform normal operation processes such as a handover, so the idle mode saves the power of the MS and air interface resources.
The areas covered by BSs may form a group named paging group. The paging group aims to constitute a continuous area. In the continuous area, the MS does not need to send uplink services, but may determine whether there are downlink services sent to the MS by a downlink paging channel. The paging group must be large enough to make sure most MSs remain in the same paging group in a long time period; at the same time, the paging group must be small enough to make sure the overhead of paging the MSs is reasonable in a paging group.
In the normal operation with a serving BS, an MS may enter the idle mode by sending a message request. Similarly, the serving BS may also request the MS to enter the idle mode by sending a message to the MS. Regardless of whether the MS forwardly initiates a request to enter the idle mode or the serving BS sends a message to request the MS initially to enter the idle mode, the MS needs to finish registering and entering the idle mode in a set period.
A paging reference model in the idle mode is defined in the WiMAX Worldwide Interoperability Microwave Access standard which is being constituted right now. A paging controller (PC) is a network entity capable of controlling activities of the MSs in the idle mode. The entity is a logic entity in the current WiMAX network architecture, and is closely associated with another logic entity, i.e., the authenticator (the PC may be realized in the same physical network element (NE) as a part of the logic function of the authenticator). The physical location of the PC is either a physical NE access service network gateway (ASN GW) of the WiMAX network or another independent physical NE. In addition, as the PC needs to initiate a paging message according to the paging group in which the current MS is located, a location register (LR) is required to store status information of the MS, paging information, and information related to service flows. Generally, a PC logic entity is corresponding to an LR logic entity, and the two logic entities are realized in the same physical NE.
Suppose other physical NEs and logical entities in the WiMAX network are not considered, FIG. 1 is a schematic diagram of a paging group network in a WiMAX network according to the conventional art. The WiMAX paging reference model according to FIG. 1 is adopted in the following technical descriptions, and the technology of the present invention includes, but is not limited to, applications in a WiMAX system.
According to the paging reference model of FIG. 1, when the MS initially requests to enter the idle mode on BS1 (Serving BS), or when BS1 instructs the MS to enter the idle mode, through the message interaction between the MS and BS1 and the message interaction between BS1 and the ASN GW (a rear NE), the PC is informed that the MS enters the idle state, wherein informing the PC is realized in ASN GW1, and the status information, paging information, and service flow information of the MS are stored in the corresponding LR. The MS may carry the information which needs to be reserved when entering the idle mode in the idle model request message sent to BS1, and BS1 may also configure similar information in an idle mode response message, adapted to inform the MS of the related information stored in the LR by the MS and the PC ID. The PC involved in the above process is an anchor paging controller (PC) serving the MS. In addition, after the MS enters the idle mode, corresponding R4 and R6 interfaces need to be released, but an R3 interface between the home agent (HA) and foreign agent (FA) needs to be reserved.
According to the above scheme, when the network needs to page the MS in the idle state, the ASN GW in which the FA is located queries information related to the MS from the ASN GW in which the anchor PC/LR is located. The anchor PC/LR obtains the paging group in which the current MS is located according to the location record, and queries about the ASN GW in which PC is located that belongs to the paging group. The APC sends a message of paging the MS to the ASN GW in which the relay PCs related to the paging group is located. The anchor PC is required to configure and manage all possible paging group information in this scheme. As each PC may be the anchor PC of a different MS, all of the PCs need such configuration and management, the data configuration volume is very large, and the management is complicated.
According to the above scheme, in the idle mode, the MS needs to initiate periodically a location updating request message over air interface to the current BS in which the MS is located. After receiving the message, the BS sends a location updating message about the rear network to the corresponding PC according to the PC ID in the message. The PC determines whether the MS enters a new paging group according to the message; and if the MS enters a new paging group, the corresponding information in the LR is updated.
The disadvantages of the above scheme are as follows:                1) The grouping of the paging groups is not limited or specified, causing the anchor PCs to need to configure and manage all possible paging groups. FIG. 2 is a schematic diagram of another conventional paging group network. As shown in FIG. 2, both paging group1 and paging group3 involve two ASN GWs. Thus, when data is delivered to the paging group in which an MS is located, the PC needs to deliver the paging message to multiple ASN GWs of the paging group in which the MS is located.        2) In a conventional system, the corresponding relationship between the paging groups and the ASN GWs need to be configured in the LR, thus resulting in unnecessary configuration and maintenance. In the situation of the paging group division shown in FIG. 2, the PC/LR needs to maintain the ASN GW information corresponding to each paging group. Otherwise, when a paging message needs to be sent to a certain MS, the PC does not know which ASN GW the paging message should be delivered to.        